Switching arrangement for automatic telephone systems



Feb. 16, 1932. K. G. JOHNSON SWITCHING ARRANGEMNT FOR `AUTOMATIC TELEPHONE SYSTEMS Filed Aug. 25, 195o l4 sheets-sheet I CA2,l

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SWITCHING ARRANGEMENT FOR AUTOMATIC TELEPHONE SYSTEMS K. cs.- JOHNSON Filed4 Aug. 25, 195o 4 sheets-sheet 2 Y' ya K. G. JOHNSON 1,845,604

SWITCHING ARRANGEMENT FOR AUTOMATIC TELEPHONE SYSTEMS Feb. 16, 1932.

l 4 Sheets-Sheet 3 Filed Aug. l25, 1930 Feb. 16, 1932. K. G; JOHNSON 158459604 SWITCHING ARRANGEMENT FOR AUTOMATIC TELEPHONE SYSTEMS Filed Aug'. 25, 1930 4 sheets-sheet 4 Patented Feb. 16, 1932 airain sir Aras KARL GEORG JOHNSON, Yor STOCKHOLM,

SWEDEN, AS'SIGNOR TO TELELEG-NAKTIE;

BOL'LGET L., M. ERICSSON,0F` STOCKHOLM, SWEDEN, A' COMPANY'- SWEDEN SWTCHING- LARRANG'EMENT FR AUTOMATIC TELEPHONE' SYSTEMS Application f1ed.,Aug11st'25, 1930,5Se1ia1 No. 477,730, Aand'rin` Sweden August 28 Y1929. Y

The present invention relates to -a :switchv-r Ving arrangement in automatic telephone' systems. More especially it relates to medium sized telephone plants ot'said kind. In proj ect-ing such plants it has hitherto been necessary Ato design the system for `a certain maxi'- mum capacity already from lthe beginningvin View of the expected` future'ldevelopments of the telephone net.' The erection' costs per subscribers line for such a system will then, however, be unproportionately high.- Systems are known which allow a successive building out of an automatic telephonev exchangey having a smal-l capacityby adding an arbitrary number of .independent exchanges of substantially the same capacity. The tralic in both directions between the differentV exchanges may then be carried over external junction lines Iwh-ich by means of non-numerical selectors disposedat'each end of the lines may be connected :to-internal junction lines in eachV one of-the difierent exchanges. Thus the'di-ferent telephone exchanges form only diiierent sections of a larger telephone exchange in-whichcasethey need not necessarily be disposed .in the same locality but may be disposed at1suitable places.

The present invention'relates to systems of the latter kind. Moreespecially it frelatesto such systems in which the Vnumericalfsele'ctors only are `adaptedvto mark thefwanted subscribers lines and junction lineswhereas the talking connections are established over separate connecting apparatus, preferably operating as searchers'. Said; numerical 1s`electors together with the apparatusco-operating therewith will Yin thevfolloweing,` on account of their purpose to `register the wanted number and to mark the linescor- Y responding thereto, be called marking Aregisters. The invention has forits object :to design such marking registers in such a-manner that the telephone-plant Amay be .extended-in above described mannerbythe additionwof new exchange sections Without .then .subjecting the marking register system to any considerab'le alterations. Forthis purpose the A marking s registers are,accord1ng to the` A1nd vention, so designed that they maymark a lines.

subscribers lineV belongingto the own exlchange section as well as a subscribers -line appertaining ,to another exchangesection and an inter-.exchange junction line exten-d'- ing to the latter exchange section. Those marking registers,,which then are made use of, are preferably of the kind which comprise, on the one hand, an impulse receiver `consisting of one or more marking selectors and, on the other, a marking relay -set usuoperate with, an impulse receiver appertaining to any exchange section. Preferably'a ally common to a plurality ofimpulseA remarking relay set is provided 'for each exchange section, each'relay set then controlling only the marking circuits 'for the corresponding exchange section.

The invention will be more closelydescribed with reference to the accompanying drawings. 'Figure' l' shows diagrammatically the mutual disposition of a number of ex change sections in a telephone plant of the kind in question. Figure 2 shows aprincipal diagram over a. telephone plant according to the invention comprisingthree sections. Figures 3a andbtak'en together present adetailed circuit diagram of suchxa telephone plant, only two sections being however shown.

In Figure l,y a number of exchange sections A, B, C, D, aremutually separated by means of dot and dash'lines. Each such section'comprises an independent automatic telephone exchangev ofarbitrary size which may be placed anywhere within the telephone` net. The dilerent exchanges are of the kind which Ause, separate setting land speaking current paths. In the figure, the speaking` paths are di'agrammatically j shown by means 'of single The' selectors 'S'al'lotted'to the subscribers operate'as preselectors or searchers and may, upon calls in a section, establish communication between two subscribers lines AL over a free one of a number of internal junction lines FL in the section. In traiiicbetween two sections, by way of example from the section A to the section B, the internal junction line FLl of the section A is connected by means of the searcher ABSl to an inter-exchange unction line AB adapted to mediate the inter-exchange trai-lic between the sections which line, by means of a Searcher ABS2 disposed at the opposite end of the line, selects a free internal junction line FL2 in the section B whereupon connection is obtained with the wanted subscribers line over his selector S2. In trafc in the opposite direction, the connection is instead preferably established over the junction line BA and the searchers BAS2 and BAS1 although also such inter-exchange junction lines may be provided, which each allow trafc in both directions. The four sections indicated in the figure are mutually connected together by means of inter-exchange junction lines AB and BA, AC and CA, AD and DA,

BC and CB, BD and DB, and CD and DC in such a manner that a subscriber in any one section may call a subscriber in any other section of the plant.

All the subscribers lines connected to the different sections are included in the same `numerical series and it is, consequently, posd telephone from his set APl and by his sesible to obtain communication with one an the same line by calling the same number from any subscribers line in the entire net. Although the plant thus technically is divided into a number of substations it constitutes, from the point of view of the subscribers, a unitary central which, as regards its operation, is identical with a central of a larger type.

Figure 2 shows principally how connections may be established between the sections A, B and C. The different sections may, by way of example, be made in accordance with the system described in the Swedish Patent No. 54.793. The subscribers apparatus AP in each section may be connected over subscribers lines AL with the appertaining relays LR and the selectors S, allotted to the subscribers lines, to any `one of a number of internal junction lines FL accessible in common for all the sections. Said interna-l j unction lines are preferably brought together in groups, to each group being then allotted a marking register R which by means of relays SR may be connected to any one of the appertaining junction lines. Said marking registers are only adapted to select and, in a certain manner, to mark the wanted subscribers line whereas the talking connection is established over the selectors S in such to the internal junction line FL to which the calling subscriber has connected himself by means of his selector S. rlhe marking registers are adapted to co-operate with the marking relay set GR common to the sections, which set controls the marking circuits MT and which may be connected to any one of the marking registers R in any of the sections A, B, C over connecting apparatus AO, which may be of any arbitrary kind such as searchers or relays, and over lines ML eX- tending'through all the sections and being Connected in multiple to the apparatus AO.

For the trai'lic between the diiferent sections, inter-exchange junction lines AB, BA, AC, CA, and BC, CB are disposed together with the appertaining searchers ABS1, ABS2, BASl, BAS2, ACSl, ACS3, OASI, CAS3.

In the following it may vbe assumed that each section has a capacity of two hundred lines, an arrangement according to Figure l having four sections and thus representing a capacity of eight hundred lines. rllhe subscribers numbers containing three digits, the first digit in the number indicating the section to which the subscriber belongs.

The establishment of a talking connection between two subscribers belonging to dilferent sections takes place iin the following manner.

After a subscriber in the one section, by way of example A, has lifted his microlector Sl has been connected to a free internal junction line, the subscriber may, in case a free marking register R1 is available, start to send the numerical impulses. As soon as the digit, by way of example designating the section C, has been dialled, the register actuates the starting relay of the Searcher ACSl. The Searcher is started and begins hunting for the internal junction line engaged by the calling subscribers set in the section A. As soon as the searcher has stopped on said line the other Searcher ACSS of the inter-eX- change junction line is started to hunt for a free internal junction line in the section C. When such a line is found the Searcher stops and the calling subscribers set APl in the section A is connected to a free internal junction line FL3 in the section C. After the subscriber has dialled the entire number the register R1 is connected over the appertaining marking line ML and the connecting apparatus A03 to the marking relay set GRS of the section C if said set hasA not been previously engaged by any register. rThe number is then transferred in known manner to GRS which closes a marking circuit over the wanted subscribers marking wire MT3. Then the called subscribers selector S3 is started and hunts for the internal junction line FL3 in section C marked over the internal junction line FLl in thesection A and over the inter-exchange junction line AC.

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Whenth'eiselector finds-said `line it stops, the subscribers linesAL1` and ALS being `then connected together over Sl-FLl-ACSf- AC"'ACS3l-FL3S3. At the same time the registerand-GRS aredisconnected to be availablefor `-new connections.-

The -registerzn the section A is not connected -tofGrR3 before the internal junction lines FLl and FLZ of the two4v sections have been united. The'marking relay set V@R3 is thus-not engaged by the register during the time when the two searchers of the junction linehuntfo'r the inter-nal junction lines in the; sections A and C respectively.

Figures 3a and 3b taken together show a circuit Adiagram fora system of that kind whichV is described with reference to Figure 2.) The marking registers R consist of a number' of'marking selectors RSH, vRST and RSU. The successive connecting into circuit of the differ-ent marking selectors takes place under the control of a. sequence switch SO of the same construction as the marking selectors. The latter areV of the rotary type and adapted tobe advanced stepwise: means of electroni agnets DRH, DRT, DRU against the action of a spring by means of which the selector is restored to the starting position after a lock magnet SMT-T, SMT, SMU has been decnergized which magnet during the setting holds the selector in set position. The registers are adapted, by means of relays GA and GC respectively corresponding to the connecting devicesAO in Figure 2, to be connected to marking relay set GR in the wanted section.Y If the wanted subscriber 'belongs to another section than the calling section the register is connected over a. line ML to the marking relay set of the section in question.

`.Tn Figures 3c and 3b there are only shown two sections A and C. It may be assumed i that the subscribers line ALl connected to the section A desires communication with a subscribers line AL3 connectedl to the section C.

When the calling subscriber lifts his micro-- telephone the line circuit 1 is closed, the relay started and in known manner hunt-s for a free junction lineV F L1. In connecting to the latterfline a current path 3 `is formed `over the third or private wire c through the test relay LY1 and connecting relay SAR. The test relay connects itself into a holding circuit over its contact 4. The .connecting relay SAR connects the junctionline FLl to a register R1 free for the time-being, the microphone circuit 5 being then simultaneously closed through the impulse receiving relay RI of the register. When RI is energized a slow acting relay RT1 is connected into circuit and closes in turna circuit 6 through'the driving magnet DR()` ofthe sequence switch SO. Parallelly with the saidv path av current path 7 is v closed through the lock magnetsSMO, SMH, SMT and SMU in the marking. selectors-:RS and the sequence switch'SO. At the :same `time the register is marked busy by closing the contact 8 of RTP When the sequenceswitch SO was actuated over the circuit 6 its Contact farms were advanced to the second position of .the sequence switch. Inthis position a current path 9 of a buzzer current'source SU is closed through a winding HL of the impulse relay RI whereby the subscribers attention is called to the fact that the register has been connected into circuit and is ready to receive the impulses. The subscriber then sends the impulses. Upon the first interruption inthe vline circuit, a circuit v10 is closed throughthe slow 4acting relay RT2 and further a circuit 11 through the driving magnet DRH of the marking selector RSH. 'By said impulses n said marking selector is now set in the position corresponding to the hundreds digit. If said digit is assumed toV appertain to a line within'the same section A, by way of example the numeral one, the marking relay 4stops thus in the second position if the selector is assumed normally to take 'up the first position. When the relay RT2 is energized the circuit 6 of the driving magnet DRG of the sequence switch SO is interrupted which driving mag- 4 net is de-energized without, however, then bringing about any advance ofthe sequence switch. After the impulses `in )the rstimpulse series have been sent the relay RT2 is de-energized the Ycircuit 6 being `then closed and bringing about a forward displacement of the sequence switch SO into the third position. Throughthe then succeeding impulse series corresponding to the tens digit in the subscribers number, the marking selector RSTHis set whereupon the sequence switch SO in similar manner as before is advanced into the fourth position. In said position of the sequence switch the third series of impulses are sent which now actuate the marking selector RSU whereupon the sequence switch SO is advanced to its fifth position aV circuit 12 being then closed over a relay AR3 of the `register..` At the same time, when the relay RT2 is deenergized, the circuit 13 is closed over.

the-contact 14 of the slow acting relay RT3. The relay A Rl is now energized and locks itself over its own contact 15 and closes a current path16 over the hundreds selecto-r BSH of the register through the marking relay.

GAl corresponding to section A in the common relay group GRl The relay GA,L is energized and closes a circuit 17 through the relay GH1 adapted for selection, within the section, of veven or odd hundreds and also a circuit 18 over the contact 19 of the relay GHI,

, through the relay OHl, .and iinally also the circuit 2O from' the tens selector through'the Yrelay OI-I-lV and the circuit 21 from the units selector over the-contact 22 of the relay OHTL f" and-through the marking -relay MB1-of the wanted subscriber and the line relay LRL. If the subscriber is free the latter .relays cause in known manner the starting of the corresponding pre-selector S1. The pre-selector S1 of the wanted subscriber hunts now in known manner for an internal junction line FLlr, the fourth wire CZ of which is marked over the relay SAM and the Contact 23 of the relay SAR. Then testing takes place over the circuit 2%. -As soon as the testing circuit 24 is closed, when the selector finds thejunction line in question, the relay SAM is energized and closes the circuit 25 for the relay STR which disconnectsthe register and closes a holding circuit for itself over its Contact 26. At the same time the microphone circuit is closed over the feed coil MS and the contact 27. The desired communication is thus completed with a subscriber within the same section and the register is restored to normal position in known manner. f

If the subscriber desires communication with another subscriber with another sec tion, by way of example the section C, whose number begins with, by way of example, the numeral 5, connection to the register and reception of the first impulse series take place in above described manner. The marking selector BSH then stops in its sixth position and when the selector RT2 after the first impulse series is de-energized the relay AR,L is energized over the circuit 13 and forms a current path 28 over the hundreds selector and the starting relay FSR of the inter-exchange junction line. The latter relay is energizedand closes an impulse circuit 29 through the driving magnet FDRl o1 the inter-exchange junction line searcher ACSl. Further the relay FSR prepares a test circuit 30 through the relay LYRl. The latter circuit is closed when the searcher ACS1 finds the junction line FLl to which the calling subscriber is connected. The circuit 30 includes a relay FBR which is energized and interrupts the impulse circuit 29 so that the selector ACS1 stops. At the same time also the relay LYR1 is also energized and receives holding current over its contact 31 and closes an impulse circuit 32 for the driving magnet FDR-3 of the inter-exchange junction line searcher ACSS. Further the relay LYR1 prepares a test circuit 33 through the relay LYR3. The latter circuit is completed when the searcher ACS3 inds a Jfree internal junction line FL3 in the section C. The circuit 33 is then extended through a busy marking relay ER3 in the section C. The

vlatter relay is energized and disconnects the register at its contact 34 of the a-wire of the internal junction line FL3 and marks the line busy over the contact 35 of the c-wire. At the same time also the relay LYR3 is energized and receives holding current over .its contact 36. The calling subscriber in the section A is thus connected to a free internal junction line in the section C.

Meanwhile the subscriberhas started send-` ing of the other impulses whereby the marking selectors RST and RSU are set as before. All the wires MLM, which are the object of the selecting operation of said selectors, may by means of relays GA31 be connected to the marking relay set G33 in the section C. In similar manner said wires may be connected through a relay GA21 to the marking relay set in a section B, Figure 2. The relays GAM, GAM, and GA31 correspond thus to parts of the connecting apparatus AOl and AO2 and AOS respectively in Figure 2. The relay @A31 is controlled by the circuit 37 which was formed in energizing the relay FER over the circuit 30 when the selector ACS1 found the junction line FLl. Through the energization of the relay GA81 there is now formed the circuit 38 through the relay GHS which, upon its energization, closes the circuit 39 through the relay CH3 and selects odd hundreds within the section C. Through the energization of the relay ,OI-T3 the circuit 40 is closed for the tens relay OHT3 and when said relay is energized the marking circuit 41 is completed through the wanted subcibers marking relay MRS and the relay 1. scriber is free, in known manner the starting of the corresponding pre-selector S3. The latter selector hunts now in known manner by means of testing in the contact field of the fourth wire the internal junction line FL3 engaged by the calling subscriber. The testing then takes place over the circuit 42 through the relay SAM in the section A. As soon as said testing circuit is closed when the selector iinds the junction line in question the relay SAM is energized and closes the circuit 2,5 for the relay STR which disconnects the register and closes a holding circuit for itself over its contact 26. At the The restoration of the talkin@ connection f takes place when the calling subscriber hooks up his microtelephone. Then the relay LR1 is cle-energized whereby the relay STR is deenergized. This results in that the relay LYB1 is cle-energized and then also the re- L.

lays 1YR@` and ERS at the contact 35 of the latter relay the circuit of the holding winding of the relay LY3 is then interrupted.

I claim:

Said relays cause then, if the subf 1. In a telephone system comprising a numi ating as searchers, and means to mark both al subscribers line appertaining to the own exchange section, and a subscribers line belonging to another exchange section and an interexchange junction line extending to the latter exchange section from the marking register belonging to the calling station.

2. A telephone system according to claim 1, in which the marking registers comprise on the one hand an impulse receiver with a num ber of marking selectors, said receiver being individually allotted to each separate exchange section and accessible only for the subscribers in the appertaining exchange section, and on the other a marking relay set cooperating with the impulse receiver to control the marking circuits of the subscribers lines, which relay set is adapted to be connected to and cooperate with an impulse receiver appertaining to any one of the differentexchange sections. Y

3. In a telephone system comprising a number of automatic telephone exchanges mutually connected by means of inter-exchange junction lines, means to connect up the subscribers lines over internal junction lines to marking registers consisting of an impulse receiver and a marking relay set cooperating with said receiver and controlling the marking circuits of the own exchange only, means to mark both a subscribers line appertaining to the own exchange and a subscribers line belonging to another exchange and an inter-exchange unction line extending to the latter exchange from the marking register belonging to the calling station.

4. In a telephone system comprising a number of automatic telephone exchanges mutually connected by means of inter-exchange junction lines, means to lconnect up the subscribers lines over internal junction lines to marking registers consisting of an impulse receiver and a marking relay set cooperating with said receiver and controlling the marking circuits of the own exchange only, means to mark both a subscribers line appertaining to the ownexchange and a subscribers line belonging to another exchange and an inter-exchange junction line extending to the latter exchange from the marking register belonging to the calling station and means to engage the marking relay set of the own exchange upon calls to another exchange first after the calling subscribers line has been connected over an inter-exchange junction line to an internal junction line in the latter exchange section.

5. In a telephone system comprising a number of automatic telephone exchanges mutually connected by means of inter-exchange junction lines, means to connect up the subscribers lines over internal junction lines to impulse receiving marking registers, means to connect up the inter-change junction lines to the internal lines over searchers which are alloted to the diiierent inter-exchange junction lines and which may be selected and started over circuits controlled by the impulse receivers.

In testimony whereof I aiiix my signature.

KARL GEORG JOHNSON. 

